Alkylation of ethylene



Sept. 18, 1945. G. T. ATKlNs, JR

ALKYLATtoN oF ETHYLENE Filed Aug. l, 1941 Patented ept. 18, 1945 ALKYLATION F ETHYLENE George T. Atiim, Jr.,

to Standard Oil Deve poration of Delaware Highlands, Tex.. assigner lopment Company, a' oor- Application August 1, 1941, Serial No. 404,981 1o claims. (ci. 26o-sass) The present invention is concerned with the production of normally liquid saturated hydrocarbons suitable for use as motor fuels. The invention more particularly relates to a method of alkylating saturated hydrocarbons containing at least one tertiary carbon atom per molecule with ethylene. In accordance with the present invention, ethylene is alkylated by utilizing, in conjunction with the saturated hydrocarbon containing at least one tertiary carbon atom in the molecule. a quantity of a higher boiling olefin.

It is known in the art that saturated hydrocarbone containing a tertiary-'carbon atom, hereinafter referred to as tertiary hydrocarbons, will react with oleilns, in the presence oi' a suitable catalyst such as concentrated mineral acids. resulting in the production oi a wide range of higher boiling hydrocarbon products. The nature of these reactions varies widely with the reaction conditions and with th'e particular type and character of feed materials employed.

The feed stocks which are employed in producing these motor fuels vary considerably. The lsoparamnic constituent of the feed stock usually comprises isobutana' isopentane and similar higher branched chain homologues contamina at least one tertiam carbon atom per molecule. The 'oleilnic reactants generally comprise propylene, normal butylenes, isobutylene, trimethyl ethylene, the isomeric pentenes and similar higher mono-oleo hydrocarbons oi' either s, straight cin or branched ch structure. Mixtures of two or more of these mono-oleins are likewise employed. Under certain operations the feed material comprises various reinery cuts segregated from various cracking and distillation operations, such as propane, butane and pentane cuts which comprise constituents .boiling in the respective boiling ranges. Other feed materials may comprise polymers.. copolymers, interpolymers and crosspolymers oi the abovementioned ol, such products being, for exple, diisobutylene, triisobutylene, tetraisobutylene, the caer, cotrimer and cotetramer of normal butylenes and isobutylene, the interdimer, interter and intertetramer oi lsobutylone with penmnes, both branched and straight chain in character, the same products formed by condensing normal butylenes with branched or straight chain pentenes and similar high boilin@ monoolennic condensation products.

lin these reactions the catalyst generally employed comprises a concentrated mineral acid as, for example, a sulfuric acid, a halosenated sulfuric acid, an acid or phosphorus or an equivation of ethylene.

lent acid. AGther satisfactory catalysts are boron fluoride, the metal haiides such as aluminum halide and iron halide, acid activated clays, as well as the mineral acids, employed in conjunction with various compounds of the nfth group of the periodic system, the aluminum halidealkali metal halide double salt complexes, and various other similar catalysts. When employing sulfuric acid the reaction is generally conducted by utilizing an acid concentration above about preferably an acid concentration in the range from about to about 100%.

The alkylation reaction is usully conducted at a relatively low temperature, that is, of the order of about 30 F. to about 100 F., preferably between about 40" F. and about 70 F. However, under certain conditions temperatures outside this range are employed. The time of the reaction varies considerably but in general is in the range from about 5 minutes to about 2*/2 hours, or longer, depending upon related operating conditions. Usually the reaction time is in the range from about 10 to about 60 minutes. Although the reaction may be carried out in the vapor phase the reaction is generally conducted in the liquid phase. In'a liquid phase operation the pressures are at least sufficient to keep the respective reactants from vaporizing. Pressures of from about 0 to about in atmospheres or pressures as high as atmospheres, depending upon the 'reaction temperature, are employed.

In these reactions although equal molecular quantities of isopar and mono-olefin may be used it has been found desirable to maintain a substantial excess oi' the tertiary hydrocarbon in the reaction sone and to operate in a reaction medium containing an excess oi' the catalyst composition. For example, in an operation wherein isobutane or isopentane is employed as the isoparaiilnic reactant, themolar excess ranges from about 1 to as high as 200 mois per mol of mono-olens present.

In these operations carried out under the above-described conditions it has not been possible heretofore to secure any appreciable la- I have, however, now disthat if a mineral acid be employed it is to alkylate ethylene providing the alkylacovered Possible tion reaction be conducted in the presence of a` as, for example, butylene.

higher boiling olefin amylene, and the like.

My process may be readily understood by rei'- erence to the drawing illustrating: an embodiment of the same. For purposes of description it is assumed that the feed ses comprises a gas sen cured from conventional refining operations and consists of hydrocarbon constituents containing from one to six and higher carbon atoms in the molecule. The feed gas is introduced into the bottom of absorption zone 2 by means oi feed line I. The feed gas flows upwardly through absorption zone 2 and countercurrently contacts downflowing absorption oil which is introduced into the top of the absorption zone by means of line l2. Temperature and pressure conditions are adjusted in zone 2 so as to absorb in the absorption oli all butane and higher boiling hydrocarbon. The absorption oil containing the absorbed constituents is removed from absorption zone 2 by means of line 3 and passed into distillation zone 4 wherein the absorbed constituents are removed from the oil. The constituents which are separated from the oil are removed overhead by means of line 20, condensed in cooling zone 2i, and passed to separation zone 22 wherein uncondensed gases are separated from the condensate. The uncondensed gases are removed by means of line 23 and preferably recycled to absorption zone 2. The condensate is removed from separation zone 22 by means of line 5 and passed t0 distillation zone 24 wherein the same is distilled to segregate a residue gas which is removed by means of line 25, a propane-propylene fraction which is removed by means ofline 26, a butanebutylene fraction which is removed by means of line 21, and a naphtha bottoms which is removed by means of line 28', which streams are handled as hereinafter described.

The vapors denuded of butane and higher boiling hydrocarbons are removed overhead from absorption zone 2 by means o f line 23, are passed through separation zone 30, compressed in compressing zone 3I, cooled in cooling zone 32, and introduced into absorption zone 9. These gases now upwardly in absorption zone 9 and countercurrently contact a stream of absorption oil secured as hereinafter described, which stream is introduced into absorption zone 9 by means of line I0. Temperature and pressure conditions are adjusted so as to absorb propane and propylene in the absorption oil as it ows down through the absorption zone. The absorption oil in the bottom of zone 9 is heated by means of reboiler means 33 so as to separate propane-propylene constituents which are removed from zone 8 by means of line 34, cooled in cooling zone 35, and passed to separation zone 36. A propane-propylene vaporous fraction is removed by means of line il, condensed in condenser 31, and withdrawn from the system as desired by means of line 38. The absorption oil, which may still contain propane-prcpylene constituents, is removed from reboiler -33 by means of line 33, cooled in cooling zone 40, and then introduced into the top of absorption zone 2 and handled as hereinbefore described. The gases comprising ethylene, methane, and the like, are removed overhead from absorption zone 9 by means of line 4|, passed to separation zone 42 from which entrained liquid may be removed by means of line 43. The gases are compressed in compressing zone 44, cooled in cooling zone 45 and introduced into absorption zone 1 wherein the same countercurrently contact, the absorption oil removed from zone d. This absorption oil is cooled in cooling zone 48 and combined with makeup oil before introducing the same into the top of absorption zone 1 by means of line 6. Temperature and pressure conditions are adjusted to remove overhead methane and other gases by means oi line 41 and to absorb in theA oil ethane and ethylene. The absorption oil containing these constituents is treated in the bottom of zone 1 by means of heating zone 8 to remove the same from the oil, which constituents are removed by means of line 43, cooled in cooling zone 49, and passed to separation zone B0. Condensed constituents are removed from zone 50 by means of line 5I and combined with the absorption oil passing to zone 9 by means of line I0. The ethane-ethylene stream is removed from zone 50 by means of line 52.

The ethane-ethylene stream segregated by means of line 52 is passed into reaction zone 58 vnear the bottom of said zone by means of jets or equivalent means 64 and 16. Operating conditions are adjusted so that the bottom of zone bil contains an acid phase. The butano-butylene stream removed from zone 24 by means of line 21 is combined with makeup isobutane which is introduced into the system by means of line 55 and the recycled isobutane which is separated as hereinafter described and which is introduced by means of line 5B. This hydrocarbon phase is introduced into the top of reaction zone 53. Acid which is withdrawn from the bottom of zone 58 is recycled to the top of said zone in the hydrocarbon phase by means of line 51. Unreacted gaseous constituents are removed from zone 53 by means oi line 58, cooled in cooling zone tu, and passed to separation zone 30. Unreacted constituents comprising methane and ethane are removed by means of line 6 I while the condensate is recycled by means of line 62. Recycle in the hydrocarbon phase may be provided by withdrawing a portion of the same by means of line B3, and cooling the same in zone 84. The cooled phase is returned to zone 53 by means of line 82. The reaction product comprising the alkylate is withdrawn by means of line 14, passed into separation zone 66 where the acid is separated and removed by means of line B6. This acid may be withdrawn from the system by means of line 81 or recycled by means of line 68. The hydrocarbon phase comprising the alkylate is removed by means of line 83 and passed to distillation zone 10 wherein the alkylate is separated by means of line 1i, the normal butane by means of line 12, and an ethane-ethylene stream by means of line 13. Isobutane is separated by means of line 56 and handled as hereinbeore described. Strong sulfuric acid is added as required to zone 53 through line 15.

The process of the present invention may be widely varied. It is to be understood that the respective zones may comprise any suitable number and arrangement of units. The invention essentially comprises alkylating ethylene by utilizing a mineral acid, isoparafiin and a quantity of a higher boiling olenn, preferably butylene. The acid preferably comprises sulfuric acid having a concentration in the range from about to about The temperatures similarly may vary in the general range from about 30 F. to about F. The concentration of inert constituents such as methane and ethane should be kept low in order to reduce the partial pressure exerted by these components. The partial pressure of ethylene should be relatively high, preferably in the range from 25 to 100 pounds per square inch or above, in order to promote a rapid rate of solution and reaction of this component. The operating pressure will depend upon temperature and concentration ot the components, their partial pressure, the quantity and the quality of the products desired, and the relative cost of the low concentration favoring alkylation by ethylene, anda still lower concentration being insumcient to induce alkylation. When a'product cont 30 volume per cent or more oi' hexane fraction is desired it is preferable to use about 25 mois of ethylene per m01 of butylene. It is preierable to withhold the higher olefin until the ethylene has dissolved and is in contact with isoparaihn and catalyst. It is preferable to add,

ing unabsorbed gas from the ethylene acid solution, adding isobutane to the ethylene acid abior each mol of olefin consumed in the reaction,

atleast one mol but preferably five or more mois ot isoparamn.

lin order to illustrate the invention further. the following example is siven which should not be construed as limiting the same in any manner whatsoever:

Eramhlc A number of operations were conducted in which feed mixtures comprising oletins were allated with tertiary hydrocarbons. The ratio of ethylene to butylene was varied. The results oi these operations were as follows:

Alleviation of isobtitone with ethylene Operation Time oi additional stirring, min 30 30 t. per cent yield based on OsHs 224 360 Wt. per cent yield based on total oleiins 168 180 Wt. r cent yield based on H4 assuming theore cal yield based on 04H0 83 160 Vo per cent Cs bit-105 F.) 1.5 2. 5

V0 per cent Ca 105-105" F. 16. 3 22. 8

V0.pet0ent C1 165-180" F. 1.3 2.2

Vo.percent Cs 18o-285W". 71.8 64.0

Vo per cent Ct above 205 F.) 0. l 8.5

From the above it is apmrent that appreciable aillylation oi ethylene is secured. Furthermore, it is apparent that it is desirable to maintain an ethylene to butylene ratio above 1:1', preferably sorption product and alkylating at a temperature between 30 l". and 130 il'. the ethylene absorption product in this mixture in the presence oi' atleast an equi-molecular amount of the isobutane and an amount of added butylene such that the mol ratio oi etlwlene to butylene is at least 1:1 and not substantially greater than 25:1.

3. A process for the manufacture of high antiknock gasoline hydrocarbons from a refinery gas consisting essentially of a mixture o! Ci to Ct hydrocarbons, which comprises tractionating the gas to separate out a Cz fraction containing ethylene and a C4 fraction containing' substantially all oi' the butylenes, alkylating the separated C: fraction at a temperature between 30 F. and 130 F. with strong sulfuric acid oi' alkyl.- tion strength in the presence of at least an equimolecular amount of isobutane and with the addition oi' a sufficient proportion of said C4 fraction to provide an amount oi' butylene auch that the mol ratio of ethylene to butylene is at least 2:1 and not substantially greater than 25:1 and stabilizing the resulting alkylation products to sepaethane, alkylatlng the ethylene absorption prodat I claim as new and wish to protect by v Letters Patent is:

i.. A process for the alkylation of a. low boiling isoparamn with ethylene to produce high antihnoclr liquid hydrocarbons within the gasoline boiling range, which comprises contacting ethylene with at least an equi-molecular amount of the low boiling isoparamn in the presence oi strong sulfuric acid of allryiation strength at tcmperatures between 30 F. and 130 il'. and with an t oi butylene such that the mol ratio oi' ethylene to butylene is at least 1:1 and not substantially greater than 25:1.

a. A process for the manufacture oi high antilrnocls goline hydrocarbons from an olefin-containing gas, the ollen content oi which consists essentially oi ethylene, which comprises absorbing the ethyle in stro uric acid. separatuct at a temperature between 30 F. and 130 F. in the presence of strong sulfuric acid of alkylation strength with at least an equi-molecular amount of isobutane and a suiiicient proportion of the C4 fraction to provide an amount of butylene such that the mol ratio of ethylene to butylene is at least 2:1 and not substantially greater than 25:1, separating the hydrocarbon alkylation products from used acid and stabilizing the hydrocarbon alkylation products to separate out a gaseous fraction containing isobutane which is recycled to the alkylation reaction.

5. A process for the alkylation of a low boiling isoparafiin with ethylene to produce high antiknock liquid hydrocarbons within the gasoline boiling range. which comprises contacting ethylene with at least an equi-molecular amount of the low boiling isoparamn in the presence of strong sulfuric aci'd of alkylation strength at temperatures between 30 F. and 130 F. and in the presence of an added amount of butylene such that the mol ratio of ethylene to butylene is at least 1:1 and not substantially greater than 25:1.

6. A process for reacting ethylene with a saturated tertiary hydrocarbon which comprises contacting the ethylene in admixture with another oleiin having at least 4 carbon atoms in its molecule, the mole ratio oi the ethylene to said other olefin in the mixture being atleast 1:1 and not substantially greater than 25:1, with said .tertiary hydrocarbon in the presence ot a mineral 4 ascuas 8. A process for reacting ethylene with a saturated tertiary hydrocarbon which comprises absorbing the ethylene in a mineral acid capable of functioning as an aikylating catalyst and contacting said mineral acid containing the dissolved ethylene with the tertiary hydrocarbon under alkyiating conditions in the presence of an olen containing at least 4 carbon atoms, there being provided not more than about 1 mole and not less than about V25 oi' a mole of said latter olefin for 1 each mole of absorbed ethylene.

9. A process according to claim 8 in which there is less than V2 a mole but not substantially less than %5 of a mole ot said latter olefin for each mole of absorbed ethylene.

10. A process according to claim 8 in which the minerai acid is sulfuric acid of the strength of between about 90% and 100%.

GEORGE T. ATKINS. JR. 

